Numerous chromatography techniques have been developed which enable the separation of mixtures into individual chemical components. Electrochromatography is one such technique. Electrochromatography involves the use of an electrical potential applied across the sorbent layer. As described in commonly owned U.S. Pat. No. 6,303,029, desirable results may be achieved by performing electrochromatography at pressures greater than atmospheric pressure. Such a technique is referred to as Planar Electrochromatography at Elevated Pressure (PPEC). Planar Electrochromatography at Elevated Pressure builds on the notion that applying pressure to the layer prevents accumulation of liquid on the surface of the layer, and also allows the removal of heat from the system. This allows the use of higher voltages, which results in higher electric fields. This causes the mobile phase to migrate more rapidly, which shortens analysis time. High pressure also decreases the space between particles in the sorbent bed, and this increases the efficiency of the system.